The present invention relates to a washing machine comprising a washing tub including an upper peripheral wall section which is stationary in a washing mode and a lower peripheral wall section which is driven to rotate clockwise and counterclockwise in the washing mode, and more particularly, relates to a washing machine arranged such that a load or loads of laundry are received in the washing tub together with water, whereby, in the case of a small amount of laundry, the laundry is caused to cycle, and is washed, due mainly to the water flow caused by the rotation of the lower peripheral wall section, and, in the case of a large amount of laundry, the laundry is washed due to the friction of the laundry against the upper peripheral wall section, as well as due to the laundry cycle caused by the frictional force produced by its contact with the lower peripheral wall section.
In a prior art washing machine of a pulsator type wherein the water flow is caused by a pulsator, the laundry is washed as it follows the cycling water. In this type of washing machine, therefore, the washing tub is required to have a capacity large enough to handle a specified size of load. This means that the amount of the load of laundry capable of being washed at one time is small. Further, where the amount of laundry to be cleaned is too small, the flow of water becomes extremely intense causing the laundry to be washed excessively. On the other hand, where the amount of laundry to be washed is too large, the speed of the flow of the water decreases correspondingly, whereby the washing effect tends to become diminished. Further, in this type of washing machine, the laundry and the pulsator come into contact with each other only accidently and partly. For this reason, it can not be expected to attain a washing-by-rubbing effect, or a washing-by-friction effect for the entire load. Stated differently, it is pointed out with respect to this type of washing machine that a load or loads of laundry are likely to be washed unevenly, and to be damaged.
Meanwhile, a washing machine has been recently proposed in which no pulsator is provided and in which the washing tub as a whole is intermittently rotated in a state wherein water and the laundry are received therein, thereby obtaining a washing effect due to the difference in flow speed between the water and the laundry. This type of washing machine has a merit in that no damage is caused to the laundry. However, it has a demerit as well in that the washing effect is small because the motion of the laundry becomes simplified due to the small difference in flow speed between the water and the laundry.